Abrasives in oral compositions debride and physically scrub the external surface of the teeth. This scrubbing action removes organic biofilm (i.e., the pellicle) on the tooth surface that is formed primarily of salivary proteins, bacteria, and bacterial byproducts. Pellicle may also be stained and discolored by foods, such as coffee, tea and berries, as well as, by tobacco smoke, cationic compounds, and chromogenic bacteria. Such physical removal of the stained pellicle is a simple and effective means of removing the undesirable surface staining and discoloration which occurs daily. Further, such physical removal of the pellicle also removes plaque bacteria on the pellicle surface, thereby minimizing the potential for gingivitis, periodontitis, and caries formation. However, oral compositions such as dentifrices should not have such high abrasiveness that potential damage to the enamel or tissue may result. As such, it is desirable to develop oral compositions that optimize the cleaning and/or polishing efficacy of the oral composition, while minimizing the harmful abrasiveness to avoid potential damage oral surfaces. Preferably, such oral compositions have a high pellicle cleaning ratio (PCR), but a low degree of dental abrasion, which is measured as radioactive dental abrasion (RDA).
In commonly accepted conventional practice, RDA values for an oral composition are generally kept below 250 to avoid harming enamel/dentin with repeated usage. However, in order to achieve a higher PCR, typically the amount and hardness of abrasives must be increased, which is conventionally known to increase the RDA. For example, it has been observed that when the RDA value of a dentifrice composition exceeds certain values, such as, e.g., above 100 to 115, the dentifrice does not necessarily exhibit a corresponding increase in the cleaning performance of the dentifrice. It has been challenging to formulate oral compositions that have a PCR of greater than 80 or 90 but still have an RDA that is below 250.